What is the earliest age that a medical professional or psychologist may be able to make a diagnosis of dyslexia in a young person?

About 7 yrs: Most professional agree that this is a diagnosis that cannot be accurately diagnosed until around 7 years of age when most people are learning to read well.

Age at reading expec: You have to wait until the age at which children are developmentally expected to read. Generally have to wait until the child falls 2 standard deviations from grade expectation. This will have to wait until 3rd grade or later. letter reversals are normal through 3rd grade.